Date of Award:
Doctor of Philosophy (PhD)
Sarah E. Null
Sarah E. Null
Robert W. Van Kirk
Multi-user water management is a challenging arena further complicated by climate change. This research is based in the Henrys Fork, Snake River, Idaho—an agricultural watershed that exemplifies those throughout the semi-arid American West. This dissertation uses an integrated approach that considers groundwater-river relationships, farm-scale decisions and basin-scale outcomes, upstream reservoir operation for downstream aquatic habitat, water rights, and collaborative stakeholder management to identify drought adaptation strategies accordingly.
Chapter 2 uses an interdisciplinary approach to quantify how improvements to irrigation efficiency at the farm-scale (i.e., converting from flood to sprinkler irrigation) can add up to affect hydrology at the landscape-scale and alter groundwater-surface water relationships. Motivated to improve economic efficiency, irrigators began converting from surface to center-pivot sprinkler irrigation in the 1950s, with rapid adoption of center-pivot sprinklers through 2000. Between 1978–2000 and 2001–2022, annual surface-water diversion decreased by 2,521 acre-ft (23%) and annual return flow to the river decreased by 2,431 acre-ft.
Chapter 3 uses streamflow predictions, local reservoir operation standards, and the relationship between groundwater and river flows to quantify 1) the potential to conduct aquifer recharge in the lower watershed under a warming climate and 2) resulting streamflow response from groundwater. Water for recharge was largely available in April and October, reducing peak springtime streamflow at the watershed outlet by 10–14% after accounting for groundwater return. Streamflow contribution from recharge peaked in July and November, increasing July–August streamflow by 6–14% and November–March streamflow by 9–14%. I demonstrate recharge can recover groundwater return flows when applied as flood irrigation on agricultural land with senior water rights.
Chapter 4 developed relationships between streamflow and habitat for three fish species in a reach where irrigation-season flows are managed by releases from an upstream reservoir. I used these relationships to 1) quantify aquatic habitat at different streamflows and 2) assess the differences in aquatic habitat across two different streamflow management histories. Using these relationships, I demonstrated that moving the management target's location and flow amount will contribute to more consistently suitable fish habitat in the reach while continuing to meet upstream management objectives.
Morrisett, Christina N., "Multi-Objective Water Management in Idaho's Henrys Fork Watershed: Leveraging Reservoir Operation and Groundwater Pathways to Benefit Aquatic Habitat" (2023). All Graduate Theses and Dissertations, Fall 2023 to Present. 7.
Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .